Calibrations

To properly reduce GPI observations one must download the proper calibrations. This document describes how the user can download all types of calibrations from the GSA. The user should read the instructions here on how to access the GSA, these instructions are only details on how to access GPI particular data.

Depending on the type of observations a program may require different type of calibrations. Calibrations are typically taken weekly or bi-monthly and the PI should search for calibrations taken within a month of the data taken in the program. It is assumed that the PI is logged in and have gone to the Search Complete Catalogue page.

Arcs

These calibrations are typically taken on a weekly basis. For each target a short arc is taken on the sky position to correct for the flexure of the instrument. Deeper arcs are taken weekly in all bands.

Follow the steps below to download the baseline arcs:

On the query page choose GPIin the Standard Query

Click on Continue to Query Form

In the form fill in "UT DATE" with ">YYYYMMDD" where YYYYMMDD is the UTDATE one month before the date of your observation.

RETURN should be 1000 rows

Observation Type set to Arc

Click on SEARCH to obtain a list of available ARCs

The figure below gives an example of filled in fields.

Astrometric Standard Field

These calibrations are typically taken on a monthly basis, and are used by the pipeline for the astrometric corrections.

Follow the steps below to download the baseline astrometric fields:

On the query page choose GPIin the User Defined Query(the query form on the left)

Click on Continue with constraint selection

Under Instrument Constraints choose Astrometric Field

Under Observing Constraints choose UT

Click on Continue with Query Constraints to obtain the search form

In the Search form fill in the following

In the form fill in "UT DATETIME" with ">YYYYMMDD" where YYYYMMDD is the UTDATE one month before the date of your observation.

RETURN should be 1000 rows

In astromtc field set the value to T

Click on SEARCH which will give you the recent Astrometric Field calibrations

The figure below shown an example query with filled in fields.

Darks

These calibrations are typically taken on a weekly basis. User should scale any DARKs using the closest exposure time as only a standard set of DARKs in certain exposure times are taken each week.

Follow the steps below to download the baseline darks:

On the query page choose GPIin the Standard Query

Click on Continue to Query Form

In the form fill in "UT DATE" with ">YYYYMMDD" where YYYYMMDD is the UTDATE one month before the date of your observation.

RETURN should be 1000 rows

Observation Type set to Dark

Observation Mode set to Any Dark

Click on SEARCH to obtain a list of available ARCs

The figure below gives an example of filled in fields.

Polarization Flats

These calibrations are typically taken on a weekly basis.

Follow the steps below to download the baseline polarization flats:

On the query page choose GPIin the Standard Query

Click on Continue to Query Form

In the form fill in "UT DATE" with ">YYYYMMDD" where YYYYMMDD is the UTDATE one month before the date of your observation.

RETURN should be 1000 rows

Observation Type set to Flat

Observation Class set to Partner Cal

Disperser set to Wollaston

Click on SEARCH to obtain a list of available polarization Flats

The figure below gives an example of filled in fields.

Polarization Standard/Telluric Standard

These standards are typically taken in open loop on a weekly basis.

Follow the steps below to download the baseline standards:

On the query page choose GPIin the Standard Query

Click on Continue to Query Form

In the form fill in "UT DATE" with ">YYYYMMDD" where YYYYMMDD is the UTDATE one month before the date of your observation.

RETURN should be 1000 rows

Science Program with Starts with set to GS-CAL

Observation Type set to Object

Disperser set to Wollaston for Polarization Standard

Disperser set to Prism for Telluric Standard

Click on SEARCH to obtain a list of available polarization Flats

The figure below gives an example of filled in fields for Polarization Standard search.

PSF Standards

PSF standards are not taken as part of the baseline calibrations. Baseline PSF correction should be accomplished by using the satellite spots.